SOLUTION: one pipe can fill a tank in 12 hours, and another can fill the tank in 8 hours. how long will it take both pipes working together to fill the tank?

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Question 547846: one pipe can fill a tank in 12 hours, and another can fill the tank in 8 hours. how long will it take both pipes working together to fill the tank?
Found 2 solutions by solver91311, josmiceli:
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


If A can do a job in x time periods, then A can do of the job in 1 time period. Likewise, if B can do the same job in y time periods, then B can do of the job in 1 time period.

So, working together, they can do



of the job in 1 time period.

Therefore, they can do the whole job in:



time periods.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Add their rates of filling
1st pipe's rate = ( 1 tank ) / ( 12 hrs )
2nd pipe's rate = ( 1tank ) / ( 8 hrs )
Let t = hrs to fill tank using both pipes
+1%2F12+%2B+1%2F8+=+1%2Ft+
Multiply both sides by +24t+
+2t+%2B+3t+=+24+
+5t+=+24+
+t+=+4.8+
+.8%2A60+=+48+
It will take 4 hrs and 48 min with both pipes